Knoxville, TN 37921 Frost Dates
Frost dates for Knoxville, TN, ZIP 37921
Around 04/01 is the usual last spring frost, about 216 days away. The first fall frost typically arrives around 11/02, about 215 frost-free days later.
The USDA Plant Hardiness Zone Map puts Knoxville in Zone 7b (5 to 10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 7b around Knoxville has about 9 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
Why 04/01 isn't a guarantee
04/01 is the middle of 30 years of NOAA records, not a promise. Plant by 03/14 and you're betting against frost in roughly 9 years out of 10. 04/17 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Knoxville compares
At roughly 215 frost-free days, Knoxville places 14,000 of 40,283 ZIP codes in this dataset. Within TN, it ranks 216 of 770.
Learn more
zone vs. frost date explains why Zone 7b and Knoxville's frost date answer different questions, and the frost range explains how to read the range around Knoxville's dates instead of trusting one.